There are conventional remaining battery capacity estimating devices adapted to measure current passed through a battery and voltage between battery terminals, estimate open-circuit voltage of the battery using battery parameters, and carry out prescribed conversion with respect to the obtained open-circuit voltage to thereby estimate the remaining battery capacity (see for example Patent Literature 1). However, the relation of the remaining battery capacity to the open-circuit voltage is known to change depending on the history of use of the battery, or in other words, have hysteresis. Therefore, the remaining battery capacity estimating device according to Patent Literature 1 cannot accurately estimate the remaining battery capacity.
In order to address the problem, according to a conventional technique, a remaining capacity in which charging is switched to discharging is obtained as a remaining capacity for switching, and the association between different states of charge and open-circuit voltage for respective remaining capacities for switching is stored, so that a remaining battery capacity can be estimated with higher accuracy (see for example Patent Literature 2).